Avast service is using 30% cpu

[Blackbird95]

I have looked at many other forums and I tried stuff, but they didn't seem to work.

First of all; Sometimes (not every time) when I start up my laptop, it seems really slow. Nothing seems to work, I'm not even able to open any programs.
I can, however, open task manager and when I do that I notice 'avast! Service (32 bit) is using around 30% of my cpu.

I have tried uninstalling it. I go to Control Panel\Programs\Programs and Features obviously and when I click uninstall on avast it gives me the option to update/change/repair/uninstall
I choose uninstall and the setup freezes. I'm unable to close it, not even through task manager.

When I go to 'open file location' of avast! Service in task manager, it opens C:\Program Files\AVAST Software\Avast
I'm unable to remove this folder. It asks me to give administrator permission. But when I do this it gives me an error saying: You need permission from an administrator to make changes to this folder.

Last time this problem persisted, I was actually able to remove this file by myself.

I tried creating a .bat file that makes me the owner of the folder as explained here: http://blog.bluetoad.net/?p=43
It gives me an error saying 'The current logged on user does not have ownership privileges on the file (folder) C:\Program Files\AVAST Software\Avast

I don't know what to do anymore. I thought I had gotten rid of it, but it returned.
For some reason it works now, but I just want to get rid of it so it won't happen again.

Thank you for your help in advance.

[DavidR]

If avast is running you won't be able to remove the avast files or folders as the self-defence module will prevent this. Removing the file avastSvc.exe (the avast service) itself wouldn't resolve the problem only disable avast.

Whilst uninstalling should resolve the avastSvc.exe (the avast service) using 30% CPU, but really it would be better to find why it is using that amount of CPU % that is the main avast scanning service/control but it doesn't just run of its own accord, there is some other activity that avast is scanning.

What were you doing when this CPU activity was going on ?
Have (or did) you another Anti-Virus installed in this system, if so what was it and how did you get rid of it ?

Some information on your system spec would be helpful, Operating System, RAM and CPU ?